I've never tried to install just one new one, have always replaced the entire set. Of course, outside of Pinball Pool this has the most drops of any game I've had. Big Indian and Surf Champ just have five targets. For that few, it was worth an entire set. I put an entire new set in PP because it had about four original targets left. It had all sorts of crazy targets in it that people had installed over the years. I saved most of them so I have some various drops stashed in case anyone ever has need for a good used one.
These are in very good shape, just a couple needed a minor touch up. There must have been a weak spot, I was just polishing the face and it snapped off.
If the number position is off like you said I'll probably spring for the entire set in the end if I can't find a good used one. The springs are all real strong and the banks are all in good condition so this is about all the target banks will need.